1. Field of Invention
The invention relates to a DC to DC converter, and particularly to a DC to DC converter with a high frequency zigzag transformer.
2. Related Art
Dc-dc converters are widely used for battery-powered electronic equipment, renewable energy systems, and voltage regulator modules (VRM) to produce a regulated voltage or current derived from an unregulated power supply. Most converters require a higher switching frequency to improve the transient response and to reduce the size of passive components. However, such a high switching frequency of hard switching converter beyond 1 MHz is not available nowadays. Therefore, multiple operations with an interleaved switching on-off control are preferable for low voltage, high current converters. The paralleled interleaving operation of the switching converter is gaining popularity because it is more efficient. The I2R conduction power loss associated with power components of each module is greatly reduced. The interleaving converter also provides ripple cancellation and improved transient response. However, parallel modules must share current equally. Current imbalance may occur due to component tolerances and/or parameter variations.
FIGS. 1 and 2 show boost and buck converter topologies with 3-phase interleaving, respectively. In FIG. 1, the boost converter, which boosts the power source 10 to the load 20, includes a first inductor L1 connected to a first diode D1, a second inductor L2 connected to a second diode D2, and a third inductor L3 connected to a third diode D3. The other terminals of the diodes D1, D2 and D3 are connected to one terminal of the load 20. A first transistor T1, a second transistor T2 and a third transistor T3 are also included. The drain terminal of the first transistor T1 is connected between the first inductor L1 and the first diode D1, while the source terminal of the first transistor T1 is connected to the other end of the load 20. The connection of the second transistor T2 and the third transistor T3 are similar to the transistor T1. A capacitor C is connected to the load 20 in parallel.
In FIG. 2, the buck converter, which bucks the power source 10 to the load 20, includes a first transistor T1 connected to a first inductor L1, a transistor T2 connected to a second inductor L2, and a third transistor T3 connected to a third inductor L3. The other terminals of the inductors L1, L2 and L3 are connected to one terminal of the load 20. A fourth transistor T4, a fifth transistor T5 and a sixth transistor T6 are also included. The drain terminal of the fourth transistor T4 is connected between the first transistor T1 and the first inductor L1, while the source terminal of the fourth transistor T4 is connected to the other end of the load 20. The connections of the fifth transistor T5 and the sixth transistor T6 are similar to the fourth transistor T4. A capacitor C is connected to the load 20 in parallel.
However, there are some technical problems in these conventional converters. For example, they require three currents sensed for current sharing purposes, and thus suffer from higher ripple current on semiconductor devices. Furthermore, the conventional converter requires many magnetic cores. For the foregoing reasons, there is need for a converter with simpler circuitry and higher efficiency.